Manual básico de reconocimiento macroscópico de algunos minerales y rocas

Memoria ID-0008. Ayudas de la Universidad de Salamanca para la innovación docente, curso 2015-2016

Atlas macroscópico y microscópico de rocas utilizadas como materiales de construcción

Memoria ID-0011. Ayudas de la Universidad de Salamanca para la innovación docente, curso 2014-2015

Cement encapsulation processes to mitigate the risks posed by different types of antimony-bearing mine waste

[EN]n this study cement encapsulation processes of different types of mine waste generated from the exploitation of Sb ore deposits were evaluated as a way to manage them and avoid further environmental pollution and the negative impact on surrounding ecosystems. For this purpose, Sb-bearing mine waste rocks, mine tailings, and smelting waste were subjected to cementation processes using Portland cement/calcium hydroxide as binder and different binder:mine waste ratios (10:90–80:20 wt%). The encapsulated materials were characterized for their mechanical behavior (compressive strength test), leaching properties (batch shaking and tank leaching tests), and mineralogical and chemical composition by X-ray powder diffraction, scanning electron microscopy, and electron microprobe analysis. A binder:mine waste ratio of 40:60 wt% was found appropriate to decrease the leachable Sb concentrations at levels below the limit for acceptance at non-hazardous waste landfills. Diffusion was the main mechanism controlling Sb leaching. The obtained effective diffusion coefficients and developed compressive strengths indicate that the encapsulated materials were suitable for disposal. Therefore, according to their leaching and strength characteristics, the encapsulated mine wastes derived using the indicated conditions could be deposited at landfills for non-hazardous waste, thus minimizing the environmental hazards caused by their accumulation in the mine surrounding areas. Additionally, according to the Dutch legislation on the use of waste materials in the built sector, some formulations of encapsulated mine tailings already met the Sb leaching requirement for open (un-insulated) construction applications. Therefore, Sb-bearing mine wastes, especially mine tailings, also present a great potential to be recycled as substitutes for natural aggregates in concrete in construction applications. Antimony was mostly preserved in the original Sb-bearing phases [Fe and Sb (oxyhydr)oxides and tripuhyite] after the encapsulation processes. Of compounds resulting from the hydration of Portland cement, C-(A)-S-H phases predominated, having an important role in attenuating the Sb release from the different types of mine waste; average Sb2O5 contents of 0.12–0.31 wt% were found in C-(A)-S-H phases

Manual de reconocimiento macroscópico de minerales y rocas con Realidad Aumentada

Memoria ID-0038. Ayudas de la Universidad de Salamanca para la innovación docente, curso 2017-2018

Arsenic distribution in a pasture area impacted by past mining activities

[EN]Former mine exploitations entail a serious threat to surrounding ecosystems as after closure of mining activities their unmanaged wastes can be a continuous source of toxic trace elements. Quite often these mine sites are found within agricultural farming areas, involving serious hazards as regards product (feed/food) quality. In this work a grazing land impacted by the abandoned mine exploitation of an arsenical deposit was studied so as to evaluate the fate of arsenic (As) and other trace elements and the potential risks involved. With this aim, profile soil samples (0–50 cm) and pasture plant species (Agrostis truncatula, Holcus annus and Leontodon longirostris) were collected at different distances (0–100 m) from the mine waste dump and analyzed for their trace element content and distribution. Likewise, plant trace element accumulation from impacted grazing soils and plant trace element translocation were assessed. The exposure of livestock grazing animals to As was also evaluated, establishing its acceptability regarding food safety and animal health. International soil guideline values for As in grazing land soils (50 mg kg−1) resulted greatly exceeded (up to about 20-fold) in the studied mining-affected soils. Moreover, As showed a high mobilization potential under circumstances such as phosphate application or establishment of reducing conditions. Arsenic exhibited relatively high translocation factor (TF) values (up to 0.32–0.89) in pasture plant species, reaching unsafe concentrations in their above-ground tissues (up to 32.9, 16.9 and 9.0 mg kg−1 in Agrostis truncatula, Leontodon longirostris and Holcus annus, respectively). Such concentrations represent an elevated risk of As transfer to the high trophic-chain levels as established by international legislation. The limited fraction of arsenite found in plant roots should play an important role in the relatively high As root-to-shoot translocation shown by these plant species. Both soil ingestion and pasture intake resulted important entrance pathways of As into livestock animals, showing quite close contribution levels. The cow acceptable daily intake (ADI) of As regarding food safety was surpassed in some locations of the study area when the species Agrostis truncatula was considered as the only pasture feed. Restrictions in the grazing use of lands with considerable As contents where this plant was the predominant pasture species should be established in order to preserve food quality. Therefore, the exposure of livestock animals to As via both soil ingestion and pasture consumption should be taken into account to establish the suitability of mining-impacted areas for gazing

Antimony distribution and mobility in different types of waste derived from the exploitation of stibnite ore deposits

[EN]Wastes derived from the exploitation of stibnite ore deposits were studied to determine their mineralogical, chemical, and environmental characteristics and establish the Sb distribution and the current and long-term risks of Sb mobilization. Representative samples of mine waste rocks, mine tailings, and smelting waste were studied by X-ray powder diffraction, polarized light microscopy, electron microprobe analysis, and digestion, leaching, and extraction procedures. The main Sb-bearing minerals and phases identified in the smelting waste were natrojarosite, iron (oxyhydr)oxides, mixtures of iron and antimony (oxyhydr)oxides, and tripuhyite; those in the mine tailings and mine waste rocks were iron (oxyhydr)oxides and/or mixtures of iron and antimony (oxyhydr)oxides. Iron (oxyhydr)oxides and natrojarosite had high Sb contents, with maximum values of 16.51 and 9.63 wt% Sb2O5, respectively. All three types of waste were characterized as toxic; the mine waste rocks and mine tailings would require pretreatment to decrease their leachable Sb content before they would be acceptable at hazardous waste landfills. Relatively little of the Sb was in desorbable forms, which accounted for <0.01 and <0.8% of the total Sb content in the smelting waste and mine waste rocks/mine tailings, respectively. Under reducing conditions, further Sb mobilization from mine waste rocks and mine tailings could occur (up to 4.6 and 3.3% of the total content, respectively), considerably increasing the risk that Sb will be introduced into the surroundings. Although the smelting waste had the highest total Sb content, it showed the lowest risk of Sb release under different environmental conditions. The significant Fe levels in the smelting waste facilitated the formation of various Fe compounds that greatly decreased the Sb mobilization from these wastes

Virtualización de clases prácticas de reconocimiento de minerales al microscopio de polarización en luz transmitida y reflejada

Memoria ID-2020/003. Ayudas de la Universidad de Salamanca para la innovación docente, curso 2020-2021

«Elaboración de un atlas de minerales de interés económico (muestras de mano y al microscopio)»

Memoria ID-224. Ayudas de la Universidad de Salamanca para la innovación docente, curso 2013-2014

Stabilization methods for the treatment of weathered arsenopyrite mine wastes: Arsenic immobilization under selective leaching conditions

40 páginas, 13 figuras, 1 tabla. -- The final version is available at www.elsevier.comThe release of arsenic from weathered arsenopyrite mine wastes represents a grave environmental issue, especially when dealing with former mining areas. The evaluation and development of measures to manage this type of wastes in a sustainable and economic way are required. In this study different methods based on the application of chemical amendments were assessed as stabilization systems. For this purpose, weathered arsenopyrite mine wastes with the occurrence of amorphous ferric arsenates (AFA)/scorodite as main secondary products, as determined by X-ray diffraction (XRD) and polarizing microscopy, were used. Stabilization studies were performed employing two different amendments applied at diverse doses, namely a combination of calcite and ferric sulfate (CC + Fe(III) salt) and a by-product generated from the processing of aluminum salt slags (BP-AlOx). The efficacy of such treatments was assessed using both batch and column leaching essays. Under the equilibrium conditions imposed by the applied standard batch leaching tests, both of the treatments at their optimal conditions attained important reductions in the leachable As concentrations (95–98% and 52–79%, respectively), making mine wastes acceptable at controlled landfills as established by international legislation. Nevertheless, under flow leaching conditions the treatment employing CC + Fe(III) salt was shown not to be an appropriate long-term stabilization method. Conversely, the treatment with BP-AlOx proved to be more perdurable, decreasing considerably the As release (>50%) under prolonged leaching conditions. This stabilization system allowed simultaneously an important transformation of AFA to scorodite. Additionally, it partially neutralized the acidity generated from mine wastes without exceeding the pH values above which the solubilization of scorodite could be enhanced importantly.The present study was carried out under the project TERMET(Grant number: RTI2018-095433-B-I00) funded by Ministerio de Ciencia, Innovación y Universidades (MCIU), Spain/Agencia Estatal de Investigación (AEI), Spain/Fondo Europeo de Desarrollo Regional(FEDER), UEPeer reviewe

Assessment of industrial by-products as amendments to stabilize antimony mine wastes

13 páginas, 9 figuras, 3 tablasThe spread of antimony from mine wastes to the environment represents a matter of great concern due to its adverse effects on impacted ecosystems. There is an urgent need for developing and adopting sustainable and inexpensive measures to deal with this type of wastes. In this study the Sb leaching behavior of mine waste rocks and mine tailings derived from the exploitation of Sb ore deposits was characterized using standard batch leaching tests (TCLP and EN-12457-4) and column leaching essays. Accordingly, these mine wastes were characterized as toxic (>0.6 mg Sb L-1) and not acceptable at hazardous waste landfills (>5 mg Sb kg-1), showing also an ongoing Sb release under prolonged leaching conditions. Two industrial by-products were evaluated as amendments to stabilize them, namely deferrisation sludge (DFS) and a by-product derived from the treatment of aluminum salt slags (BP-Al). Mine wastes were amended with different doses (0-25%) of DFS or BP-Al and the performance of these treatments was evaluated employing also batch and column leaching procedures. The effectiveness of DFS to immobilize Sb was much higher than that exhibited by BP-Al. Thus, treatments with 25% BP-Al showed Sb immobilization levels of approximately 33-53%, whereas treatments with 5 and 25% DFS already attained Sb immobilization levels up to approximately 80-90 and 90-99%, respectively. Mine tailings amended with 5% DFS and mine waste rocks amended with 25% DFS decreased their leachable Sb contents below the limit for non-hazardous waste landfill acceptance (<0.7 mg Sb kg-1). Likewise, these DFS treatments were able to revert their toxic characterization. Moreover, the 25% DFS treatment showed to be a long-lasting stabilizing system, efficient at least during a leaching period equivalent to 10-year rainfall with a great Sb leaching reduction (close to 98%). After this long-term leaching process, DFS-treated mine wastes kept their non-hazardous and non-toxic characterization. The amorphous Fe (oxyhydr)oxides composing DFS were responsible for the important Sb removal capacity showed by this by-product. Thus, when DFS was applied to mine wastes mobile Sb was importantly fixed as non-desorbable Sb, showing also a considerable Sb removal capacity in presence of strong competing anions such as phosphate. The application of DFS as amendment presents a great potential to be used as a sustainable long-term stabilizing system of Sb mine wastes.The present study was carried out under the project TERMET (Grant number: RTI 2018-095433-B-I00) funded by Ministerio de Ciencia e Innovación (MCIN), Spain/Agencia Estatal de Investigación (AEI), Spain and by Fondo Europeo de Desarrollo Regional (FEDER) "A way of making Europe", European Union, and the project “CLU-2019-05–IRNASA/CSIC Unit of Excellence”, funded by the Junta de Castilla y León (Spain) and cofinanced by the European Union [European Regional Development Fund (ERDF) “Europe drives our growth”].Peer reviewe